A Post Hoc Comparison of the Effects of Lisdexamfetamine Dimesylate and Osmotic-Release Oral System Methylphenidate on Symptoms of Attention-Deficit Hyperactivity Disorder in Children and Adolescents

INTRODUCTION There are limited head-to-head data comparing the efficacy of long-acting amfetamine- and methylphenidate-based psychostimulants as treatments for individuals with attention-deficit hyperactivity disorder (ADHD). This post hoc analysis provides the first parallel-group comparison of the effect of lisdexamfetamine dimesylate (lisdexamfetamine) and osmotic-release oral system methylphenidate (OROS-MPH) on symptoms of ADHD in children and adolescents. STUDY DESIGN This was a post hoc analysis of a randomized, double-blind, parallel-group, dose-optimized, placebo-controlled, phase III study. SETTING The phase III study was carried out in 48 centres across ten European countries. PATIENTS The phase III study enrolled children and adolescents (aged 6-17 years) who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for a primary diagnosis of ADHD and who had a baseline ADHD Rating Scale IV (ADHD-RS-IV) total score of 28 or higher. INTERVENTION Eligible patients were randomized (1:1:1) to receive a once-daily, optimized dose of lisdexamfetamine (30, 50 or 70 mg/day), placebo or OROS-MPH (18, 36 or 54 mg/day) for 7 weeks. MAIN OUTCOME MEASURES In this post hoc analysis, efficacy was assessed using the ADHD-RS-IV and Clinical Global Impressions-Improvement (CGI-I) scale. Responders were defined as those achieving at least a 30% reduction from baseline in ADHD-RS-IV total score and a CGI-I score of 1 (very much improved) or 2 (much improved). The proportion of patients achieving an ADHD-RS-IV total score less than or equal to the mean for their age (based on normative data) was also determined. Endpoint was the last on-treatment visit with a valid assessment. Safety assessments included treatment-emergent adverse events (TEAEs) and vital signs. RESULTS Of the 336 patients randomized, 332 were included in the safety population, 317 were included in the full analysis set and 196 completed the study. The mean (standard deviation) ADHD-RS-IV total score at baseline was 40.7 (7.31) for lisdexamfetamine, 41.0 (7.14) for placebo and 40.5 (6.72) for OROS-MPH. The least-squares (LS) mean change (standard error) in ADHD-RS-IV total score from baseline to endpoint was -24.3 (1.16) for lisdexamfetamine, -5.7 (1.13) for placebo and -18.7 (1.14) for OROS-MPH. The difference between lisdexamfetamine and OROS-MPH in LS mean change (95% confidence interval [CI]) in ADHD-RS-IV total score from baseline to endpoint was statistically significant in favour of lisdexamfetamine (-5.6 [-8.4 to -2.7]; p < 0.001). The difference between lisdexamfetamine and OROS-MPH in the percentage of patients (95% CI) with a CGI-I score of 1 or 2 at endpoint was 17.4 (5.0-29.8; p < 0.05; number needed to treat [NNT] 6), and the difference in the percentage of patients (95% CI) achieving at least a 30% reduction in ADHD-RS-IV total score and a CGI-I score of 1 or 2 was 18.3 (5.4-31.3; p < 0.05; NNT 6). The difference between lisdexamfetamine and OROS-MPH in the percentage of patients (95% CI) with an ADHD-RS-IV total score less than or equal to the mean for their age at endpoint was 14.0 (0.6-27.4; p = 0.050). The overall frequency of TEAEs and the frequencies of decreased appetite, insomnia, decreased weight, nausea and anorexia TEAEs were greater in patients treated with lisdexamfetamine than in those treated with OROS-MPH, whereas headache and nasopharyngitis were more frequently reported in patients receiving OROS-MPH. CONCLUSIONS This post hoc analysis showed that, at the doses tested, patients treated with lisdexamfetamine showed statistically significantly greater improvement in symptoms of ADHD than those receiving OROS-MPH, as assessed using the ADHD-RS-IV and CGI-I. The safety profiles of lisdexamfetamine and OROS-MPH were consistent with the known effects of stimulant medications.